Flotation of nickel sulfide ores

ABSTRACT

WHEREIN X is oxygen or sulfur and R is hydrogen or a hydrocarbon radical containing from 1 to 10 carbon atoms; R1 is a lower alkylene group, and R2 is a hydrocarbon radical containing from 1 to 7 carbon atoms. The collectors are used primarily in the selective recovery of sulfide minerals of nickel, but are also effective for collection of sulfide minerals such as copper, cobalt, or molybdenum from some pulps.   A method of concentrating nickel sulfide ores by flotation which comprises subjecting the ore in the form of a pulp to a flotation process in the presence of an effective quantity of a flotation collector comprising a dithiocarbamate compound corresponding to the formula

United States Patent Harris et al. Dec. 3, 1974 [54] FLOTATION 0F NICKEL SULFIDE ORES 3.590.999 7/1971 Norris et al 209/166 [75] Inventor-s: Guy H. Harris, Concord, Calif.;

David J. Collins, Darwin, Australia Znmary j l i g g L h d ttorney, gen 0r zrmoger oc ea [73] Assignee: The Dow Chemical Company,

Midl d, Mich. 57 ABSTRACT [22] Flled' 1973 A method of concentrating nickel sulfide ores by flo- [21] Appl. No: 425,409 tation which comprises subjecting the ore in the form Related Application Data of a pulp to a flotation process in the presence of an c f f S N '04 609 F b 8 effective quantity of a flotation collector comprising a ;g 0 c dithiocarbamate compound corresponding to the formula [30] Foreign Application Priority Data Feb. 8, 1973 Malagasy Republic 54830 RXRifi Feb. 5, 1973 Australia 51809/73 S wherin X is oxygen or Sulfur and R is hydrogen or a [58] i H66 167 hydrocarbon radical containing from 1 to 10 carbon 0 atoms; R is a lower alkylene group, and R is a hydro- 56] R f Cit d carbon radical containing from 1 to 7 carbon atoms.

e erences e The-collectors are used primarily in the selective re- UNITED STATES PATENTS covery of sulfide minerals of nickel, but are also effec- 2,375,083 5/l945 Coupel 260/455 A [ive for collection of sulfide minerals such as copper, 3,098,001 7/1963 Werres 260/455 A obalt or molybdenum from some pulps 3,118,924 1/1964 Norman 260/455 A 3.590.997 7/1971 Norris et al 209/166 10 Claims, No Drawings FLOTATION OF NICKEL SULFIDE ORES This application is a continuation-in-part of copending application Ser. No. 224,609, now abandoned filed Feb. 8, 1972.

BACKGROUND OF THE INVENTION The present invention relates to an ore flotation method which employs certain dithiocarbamate compounds as the flotation agent. Flotation is a process of treating a mixture of finely divided mineral solids, e.g.,

a pulverulent ore, suspended in a liquid whereby a portion of such solids are separated from other finely divided mineral solids, e.g., clays and the like materials present in the ore, by introducing a gas (or providing a gas'in situ) into the liquid to produce a frothy mass containing certain of the solids on the top of the liquid, and leaving suspended (unfrothed) other solid components of the ore.

Flotation is based on the principle that introducing a gas into a liquid containing solid particles of different materials suspended therein causes adherence of some gas to certain suspended solids and not to others and makes the particles having the gas thus adhered thereto lighter than the liquid. Accordingly, they rise to the top of the liquid to form a froth.

Various flotation agents have been admixed with the suspension to improve the frothing process. Such added agents are classed according to the function to be performed: collectors, e.g., high carbon chain compounds such as collectors for sulfide minerals including xanthates, thionocarbamates, and the like; frothers which impart the property of forming a stable froth, e.g., natural oils such as pine oil and eucalyptus oil; modifiers such as activators to induce flotation in the presence of a collector, e.g., copper sulfate; depressants, e.g., sodium cyanide, which tend to prevent a collector from functioning as such on a mineral which it is desired to retain in the liquid, and thereby discour age a substance from being carried up and forming a part of the froth; pH regulators to produce optimum metallurgical results, e.g., lime, soda ash and the like.

US. Pat. No. 3,590,999 describes flotation of sulfide ores using thionocarbamate analogues of the dithiocarbamates employed in the process of the present invention.

It is of importance to bear in mind that additaments of the above types are selected for use according to the nature of the ore, the mineral sought to be recovered, and the other additaments which are to be used in combination therewith.

An understanding of the phenomena which makes flotation a particularly valuable industrial operation is not essential to the practice 'of the present invention. They appear, however, to be largely associated with selective affinity of the surface of particulated solids, suspended in a liquid containing entrapped gas, for the liquid on one hand and the gas on the other.

The flotation principle is applied in a number of mineral separation processes among which is the selective separation of such minerals as sulfide copper minerals, sulfide zinc minerals, sulfide molybdenum minerals and others from sulfide iron minerals.

The present invention concerns the use of an unique class of compounds ascollection agents in a flotation process. It cannot reasonably be expected that any one type of collector will show superior nickel recoveries with all sulfide nickel ores. However, as will be seen from the examples herein, the collectors of the present invention give substantially improved nickel recoveries with the majority of such ores. An improvement of as much as a fraction of a percent in a large tonnage operation can constitute an important increase from the standpoints of both economics and efficiency of natural resources utilization. In general, the improvement effected by use of the present dithiocarbamate collectors over the corresponding thionocarbamates is considerably more than a fraction of a percent and with at least one ore, is as much as a 159 percent increase (see Example 8). I

SUMMARY The present invention is the improvement in the process of concentrating sulfide minerals of nickel by froth flotation which comprises contacting a sulfide nickel ore in the form of a pulp with a flotation collector comprising a compound corresponding to the formula wherein R represents H, or a hydrocarbyl group containing from one to 10 carbons, R, is an alkylene moiety containing from one to five carbons, R is a hydrocarbyl radical containing from one to seven carbons and X is O or S.

By the term sulfide nickel ore is meant any mineral deposit having a sufficient content of one or more metals to be economically processable by flotation and including as one of those metals nickel in the form of a sulfide mineral thereof. Other metals which are often present in such ores and which can also be collected as sulfides by the above defined compounds are copper, cobalt, zinc and molybdenum. The above definition is meant to include mineral deposits in which the content of nickel sulfides does not alone suffice to make the deposit economically processable.

DETAILED DESCRIPTION OF THE INVENTION tlon techniques.

In the above definition of R, the term hydrocarbyl group" means one of the following groups: linear or branched alkyl groups of one to 10 carbons;

linear or.branched alkenyl groups of two to 10 carbons;

cycloalkyl groups of three to seven carbons; cycloalkenyl groups of four to six carbons; cycloalkyl or cycloalkenyl groups having from three to seven carbons in the ring and having a hydrogen replaced by an alkyl or alkylene group of one to four carbons; a phenyl group; an alkylphenyl group or phenalkyl group of seven to 10 carbons; an alkenylphenyl or phenalkenyl group of eight to 10 ,carbons. Preferably, R is H or a linear or branched alkyl group of one to six carbons. Particularly preferred are those compounds in which R is methyl, ethyl, n-propyl or isopropyl.

In the above definition of R the term alkylene moiety means a linear or branched alkylene group of one to five carbons. Preferably, R is CH -CH CH(C1-1 )CH C11 -CH(C1-1 or CH- CH CH In the preceding definition of R the term hydrocarbyl radical means one of the following radicals:

linear or branched alkyl radicals of one to seven carbons;

linear or branched alkenyl radicals of two or seven carbons;

cycloalkyl radicals of three to seven carbons;

cycloalkenyl radicals of four to six carbons;

cycloalkyl or cycloalkenyl radicals having from three to seven carbons in the ring and having a hydrogen Examples 1-5 Various species of flotation collector compounds within the scope of the present invention were employed in the flotation recovery of copper and molybdenum values from a sulfide ore (San -Manuel) obtained from S.W. United States, employing the following procedure: An ore sample was wet ground for 4 minutes at 62.5 percent by weight solids with 1.0 lbs/ton of lime and 0.016 lbs/ton of collector. The pulp was then conditioned for 1 minute with 0.136 lb./ton of a standard frother. The pulp was then floated for 5 minutes and the concentrate and tailings assayed for copper, molybdenum and iron.

The specific collector compounds of the present invention employed, and recoveries are set forth in the following Table l. The results demonstrate the ability of the compounds of the present invention to act as collectors for other sulfide minerals which may also be present in sulfide nickel ores.

TABLE I Cu Fe Mo Example Collector Percent i Rec. Percent Rec. Percent Rec.

OH -SC H I IiiSCH(CHz)z HOC2H4 I- C S CH(CH )2 CzH OC H,-I I( JSCH(CHa)2 4 II S 16. T 52. 6 17. G 17. 3 0. 5-1 77. 4

C 1I S C 2H I 1( S C2U 5 II S 16.1 53. 3 18. 2 ll). 0 0. 52 8L. 1 @SCglhdI-(" SCill Example 6 replaced by an alkyl or alkylene group of one to four carbons; a phenyl group; a methylphenyl or benzyl radical. Preferably, R is an alkyl or alkenyl group of threeto six carbons, the isopropyl radical being particularly preferred.

1n the preceding definition, wherein X is either oxygen or sulfur, oxygen is preferred.

The flotation collector compounds as defined herein 7 are particularly effective in flotation processes used to separate and concentrate nickel and molybdenum sulfides and similar minerals from sulfide ores. In such process, a pulp is first prepared by wet grinding a sulfide containing ore to a suitable particle size, with or without a pH modifier. A suitable frothing agent is then added, e.g., pine oil, cresylic acid, polyalkoxy-paraffin and the like. An effective quantity of the flotation collector compound, as defined herein, is then added in an amount usually ranging from about 0.01 lb. to about 0.25 lb. per ton of pulp and the pulp is then agitated and aerated. The nickel and molybdenum sulfides and other like sulfide minerals collect as a froth which is readily overflowed or skimmed off from the residual gangue and non-desired materials and the metal values therein recovered.

The following Examples will facilitate a more complete understanding of the present invention but they are not meant to limit the scope of the invention to the specific embodiments incorporated therein.

Some of the collectors employed in Examples 1-5 were further tested on a nickel sulfide ore (Lynn Lake) from Canada, a copper sulfide ore from North Central United States and a molybdenum sulfide ore from SW. United States.

For the nickel ore, the ore sample was ground for 5 minutes at 60.5 percent solids with 0.4 lbs/ton of lime and 0.09 lbs/ton of collector. The pulp was conditioned for 1 minute with 0.064 lb./ton of a standard frother. The pulp was then floated 5 minutes and the tailings assayed for copper, iron and nickel.

The copper ore from North Central United States was treated in the following manner: Samples of ore were ground for 5 minutes at a pulp density of 62.5 percent solids with 0.8 lbs/ton of lime and 0.128 lbs/ton of collector. The pulp was then transferred to a commercial laboratory flotation cell and conditioned for 1 minute with 0.094 lbs/ton of a standard frother. A concentrate was then removed in 5 minutes of flotation at a pH of 9.7. The concentrate and tailings were filtered, dried and assayed; results are presented below.

The molybdenum ore from S.W. United States was tested in the following manner: Samples of ore were ground for 4 minutes at a pulp density of 62.5 percent solids with 0.4 lbs/ton of lime and 0.048 lbs/ton of collector. The pulp was then transferred to a commercial laboratory flotation cell and conditioned for 1 minute with 0.078 lbs/ton of a standard frother. A concentrate V was then removed in 5 minutes of flotation at a pH of 9.7. The concentrate and tailings were filtered, dried Example 8 and assayed; results are Presented below- In further tests, the dithio compound of Example 3 Table ll summarizes the data. was compared to the thiono analogue of U.S. Pat. No.

TABLE ll Cu 9 Fe Mo Ni Ore Collector Rec. Rec '7 Rec '7( Rec N1 Ex. 1 3.3 86.2 21.6 27.2 3.3 59.4 N1 Ex. 2 3.5 86.8 18.8 21.0 2.7 42.5 N1 Ex. 3 3.3 89.7 19.3 25.3 3.3 58.3 N1 Ex. 4 3.5 84.7 26.6 29.3 1 3.8 57.6 N1 Ex. 5 3.6 85.0 27.4 29.8 3 6 53.9 C11 Ex. 1 ll.8 25.8 5.0 2.2 Cu E11. 2 12.0 33.5 4.9 2.6 C11 Ex. 3 13.0 45.0 4.6 2.9 M6 Ex. 1 17.8 19.0 10.4 81.1 M0 Ex. 2 14.0 10.4 12.7 79.1 M6 Ex. 3 14.9 12.8 11.8 77.0

Example 7 3,590,999 in otherwise identical flotation procedures For comparison, the thionocarbamate analogs of sevon replicate pulps of five different copper-nickel ores.

Ore

Percent Lbs/Ton Recoveries Increase In Collector Used k Cu 76 Ni Nickel Recovery Great Boulder Ore (Australia) T111666 Cmpd. .300 44.12 72.92 2.56" 0111116 Cmpd. .300 44.60 74.79

lnco Ore (Canada) ThlOnO .186 91.32 79.59 5.45 DllhiO .186 91.59 83.93

Lynn Lake (Canada) ThlOnO .090 89.00 39.00 49.5 Dithio .090 89.70 58.30

WMC-A (Australia) T111666 .500 80.63 36.99 90.6 DithlO .500 85.09 70.53 1 T111666 1.60 88.20 33.10 158.6 13111116 1.60 91.80 85.60

(Acid Circuit) WMC-C (Australia) ThlOIlO I .500 63.32 73.20 7.78 131011 .500 65.42 78.89 ThlOnO 1.60 69.40 79.70 4.77 Dlfl'llO 1.60 69.30 83.50

NOTES:

C,11,-o-1:1-1 C11,--Nu cos cmcfl 2 C H,O-CH,CH,NHCS -CH(CH 7 3 Calculated as: 74.7972.92/72.92 I00 eral of the present dithio compounds were tested in the Example 9 5O Same manner Comparative tests were earned out s1de by s1de on i g ate og identical portions of ore pulps prepared from the matecH1s-c1H1No0-cH(cH1 2 rials and in the manner described in Example 6 above. The following additional comparisons were made:

H S (Thionocarbamate analo 1 11 16 Ex.2.) g 5-5 H s HOC6H1NCOCH(CH;)Q

SC2H1NCSCH(CHa)z(new;-85% pure) Comparable results were noted for the copper and molybdenum ores. However, the recoveries of nickel sulfide' from the nickel ore were substantially greater for H s I l I I the present d1th1o compounds over the th1ono analog. 60 (art);

Compound of d Example: 3 Ni Recovery an H s l (Dithio compound) 59.4 1 ll Thiono analog comparative 46.4 65 -SC2H4NCS-C11H13 (n E mpl 2 (Dithio compound) 42.5 II Thinno analog comparative 27.0

S 4 (Dithio compound) 56.2 I H Thinno unulng comparative 37.7 0 b-(.l2ll1N-COCall1a (art).

Comparison I was made at two different loadings of the collector compounds on each of two ores; a Canadian copper-nickel ore (Inco), and an Australian, high talc content copper-nickel ore (Karnbalda);

The amount of the Kambalda ore available was not sufficient for inclusion in comparison 11. Three different loadings were employed in the latter comparison;

The procedure followed with the lnco ore was as follows: A 500 gram sample of ore was ground for 7 minutes at a pulp density of 62.5 percent solids together with the collector being tested (0.33 or 0.68 lbs/ton of a percent solution in iso-butyl alcohol/acetone) and enough lime (0.05 grams) to provide a pH of 8.4. The pulp was then transferred to a commercial laboratory flotation cell and conditioned for 1 minute. 4 cc of percent aqueous sodium silicate was added and conditioning continued for 30 seconds. 0.076 lbsjton of a frother, polypropylene-butylene glycol mono methyl ether, was added and conditioning continued another 30 seconds. A first concentrate was removed in 4 minutes of flotation. Another 0.046 lbs/ton of the frother was added to the cell and flotation continued for 4minutes more to produce a second concentrate. The con centrates were combined, dried and assayed. The tailings were also recovered, dried and assayed;

The procedure used with the Kambalda ore (a very difficult ore to process) was as follows. A 500 gram sample of ore was ball-milled for 5 minutes with 300 ml. of water, sufficient lime (0.2 gram or 0.5 grams) to provide a pH of 8 or 8.2 and 0.33 lbs/ton ofa 5 percent solution of the collector in isobutyl alcohol/acetone. The pulp was then transferred to the flotation cell and conditioned for 2 minutes with 0.067 lbs/ton of methyl isobutyl carbinol frother. Concentrate was removed over a 7-minute period of flotation. The dried concentrate and tailings were assayed;

The data for comparisons l and II are given in Tables A and B following;

TAB LE B Continued ORE lNCO (pH 8.7)

Metal Nickel Wt. Percents Cone. Collector: Grade K Rec."

Compound Loading No./Ton

ART 0.042 4.65 55.32 NEW 1 5.53 62.28 ART 0.063 4.41 52.41 NEW 5.72 62.8)

" Concentration of metal in the concentrate 74 of metal in heads reporting in concentrate; i.e.. recovery 5 Averages of duplicates Flotation collectors as defined herein are prepared by several methods well known in the art.

For example, the three common methods for the preparation of compounds useful in our process are outlined below:

( Nagcsgg ZRQBI' ZNaBI' (2) RXR Nl-l CS base, e.g., KOH

R-X-R NHCS K+H O RXR,NHCS K (3) RX-R,NH R SCSCl base (e.g., pyridine) RXR,NHCS R C l-1 N l-lCl where R, R R and X are the same as defined hereinbefore. I

As an example of the first method, when a thiol compound corresponding to the formula RSH, wherein R is the same as hereinbefore defined, is contacted with ethylenimine, an amine compound corresponding to the formula R S CH CH NH is formed. This product is then contacted with a trithiocarbonate ester to prepare a compound within the scope of the present invention corresponding to the formula TABLE A Ore Inco (pH 8.4) Kambalda (pH 7.0)

Metal Copper Nickel Copper Nickel Iron Wt. pereents- Collector. Cone. Cone. Gone. Cone. Cone.

grade Rec. grade Rec. grade Rec. grade Rec. grade Rec.

- Loading, Compound lb./ton

Art. 1 h} 0 0165 4. 6 85.07 4. 2 56. 5 1. 2 45. 0 11. 1 31. 5 17. 6 18. 8 New 4. 5 84. 7 4. 4 60. 5 1. 3 42. 0 10. 3 25. 8 18. 6 17. 7

Art I o 0330 4.8 85.8 4.5 59.3 1.1 53.3 12.9 47.9 New l 4.8 84.3 4.7 61.5 1.2 45.3 11.8 36.6

1 o-s c2nr-N -0cH cHl t l 0-SC:IIl-N-fi-SC11(C1102 II S 3 Concentration 01 metal in the concentrate. H Percent of metal in hands reporting in concentrate; i.e. recovery. ll l 9 lPl 9? i TABLE B wherein R is the same as defined hereinbefore. Other amine compound starting materials can be prepared by methods well known in the art. For example, reference may be made to Wagner & Zook, Synthetic Organic Chemistry, p. 787-796, 801-805 (1953).

In another preparative process a compound corresponding to the formula wherein Y is H or a lower-alkyl, is reacted with an alcohol or thiol compound corresponding to the formulas ROH, RSH respectively, wherein R is the same as defined hereinbefore, to prepare compounds corresponding to the formulas ROCH CHY CN, RSCH CHY CN, respectively. These compounds are then contacted with a reducing agent such as LiAlH or H over a catalyst to provide compounds corresponding to the formulas l ROCH CHCHr-Nll and RSCH2CHCH2NH2,

respectively. These products can then be reacted as in preceding method 2 with carbon disulfide and a base followed by reaction with the appropriate reactive halide to provide products corresponding to the formulas respectively, whegein R; is

the same as previously defined.

The dithiochloroformate starting materials can be prepared by reacting a thiol with thiophosgene to provide a compound corresponding to the formula wherein R is the same as defined hereinbefore. Other starting materials and process schemes can also be employed in preparing the flotation collectors useful in the process of the present invention.

Several specific examples showing methods of preparation are given below.

Example Methyl 3-(Methylthio)propytdithiocarbamate To 13.8 grams (0.] mole) of dimethyl trithiocarbonate was added 10.5 grams (0.1 mole) of 3-methylthiopropylamine. Methyl mercaptan was evolved from the exothermic reaction mixture. After the reaction had ceased, the product was heated to 50-60C. under 30 mm. of pressure to remove the remaining methyl mercaptan. The structure of the liquid product was confirmed by infrared and NMR analysis.

Example 11 & Allyl 3-methoxypropyldithiocarbamate To 44.5 grams of S-methoxypropylamine in 200 ml. of isopropanol was added 19 grams of carbon disulfide followed by one-half of 32.5 grams of KOH in 250 ml. of isopropanol. Subsequently-9.5 grams of CS was added followed by one-fourth of the KOl-l solution. The remaining CS was added and then the last of the KOH solution. To the resulting potassium salt was added 38 grams of allyl chloride. After more than three hours had elapsed, water was added and the brine layer was discarded. Removal of the alcohol and any remaining brine gave 93.4 grams of product that assayed better than 90 percent pure by NMR analysis. The infrared spectrum confirmed the structure.

Example 12 lsopropyl 2-Ethoxyethyldithiocarbamate, (Table 1, Example 3) To a cooled solution of 2-ethoxyethylamine l 8 grams; 0.2 mole) in anhydrous ethyl ether was added isopropyl dithiochloroformate (15.4 grams; 0.1 mole). After several hours, pentane was added and the organic solution was washed with H O, dried and concentrated. The product was obtained in 64 percent yield by distillation, b.p. 115C. at 0.4 mm.

Anal; Caled. for C,,H -,NOS C, 46.3; H, 8.3; N, 6.8.

Found: C, 43.8; H, 8.5; N, 7.1.

Example 13 lsopropyl 2-Methylthioethyldithiocarbamate, (Table 1, Example Calcd. for C H ,NS C, 40.2; H, 7.2; N, 6.7 Found: C. 39.7; H, 6.8; N, 6.8.

Anal:

'AnaL:

Example 14 lsopropyl .2-Hydroxyethyldithiocarbamate, (Table 1, Example 2) 2-Hydroxyethylamine (16.5 grams; 0.27 mole) was treated with isopropyldithiochloroformate (20.6 grams; 0.134 mole) in anhydrous ethyl ether as in Example 10. The product was purified by percolating through a silica gel column by elution with methylene chloride. It was a yellow oil, and obtained in a 61 percent yield.

Calcd. for C H NOS C, 40.2; H, 7.3; N, 7.8. Found: C, 40.0; H, 7.4; N, 7.9.

Example 15 Ethyl 2-Octylthioethyldithiocarbamate,

(Table 1, Example 4) To a solution of ethyl diisopropylamine (12.9 grams; 0.1 mole) in ethanol ml.) was added carbon disulfide (7.6 grams; 0.1 mole) and 2-octylthioethylamine (18.9 grams; 0.1 mole). The reaction was stirred for an hour to insure salt formation, and then ethyl bromide (10.9 grams; 0.1 mole) was added. After standing overnight, the ethanol was removed under reduced pressure to yield a syrup. Ethyl ether then was added to induce crystallization of ethyl diisopropylamine hydrobromide, which was removed by filtration. (This last step was found to be necessary, as this particular hydrobromide does have some solubility in organic solvents). The ether solution was washed with water, 0.1 N HCl and then aqueous sodium bicarbonate. Removal of the ether yields the product, an amber oil, in 92 percent yield.

Found: C, 53.4; H, 9.5; N, 4.9.

Example 16 Hexyl 2-Phenylthioethyldithiocarbamate, (Table 1, Example This product was prepared in a like manner as Example 12 to give a yellow oil in a 92 percent yield on a 0.1 mole scale.

Anal.: Calcd. for C H Ns z C, 57.5; H. 7.4; N, 4.5.

Found: C, 57.5; H, 7.4; N, 4.7.

Example 17 Methyl-Z-Hydroxyethyldithiocarbamate To dimethyltrithiocarbonate (27.6 grams; 0.2 mole) was added ethanolamine (12.2 grams; 0.2 mole). The flask was cooled with an ice bath sufficiently so that the reaction temperature did not rise above 40". After the evolution of methyl mercaptan had ceased, a water pump vacuum was applied to remove any dissolved methyl mercaptan. The IR spectrum had absorption bands at 2.9-3.2 p. (OH and NH broad and strong) and ,uC S

Other compounds useful as flotation collectors are prepared in a manner similar to those set forth hereinbefore and are characterized by the general formula H I R-X-R1I Id.-sR,

wherein R, X, R, and R are as set forth in the following Table III.

We claim:

1. In the process of concentrating sulfide minerals of nickel by froth flotation, the improvement which comprises contacting a sulfide nickel ore in the form of a pulp with a flotation collector comprising a compound corresponding to the formula 6. The process of claim 1 in which R is an alkyl or alkenyl group of three to six carbons.

7. The process of claim 1 in which R is H, methyl, ethyl, propyl or isopropyl, R is CH CH CH(CH )CH -CH Cl-l(CH or CH- CH CH and R is an alkyl or alkenyl group of three to six carbons.

8. The process of claim 7 in which R is methyl, ethyl, propyl or isopropyl.

9. The process of claim 7 in which R is H, R is Cl-l- Cl-l R is isopropyl and X is O.

10. The process of claim 7 in which R is ethyl, R is -Cl-l Cl-l R is isopropyl and X is O. 

1. IN THE PROCESS OF CONCENTRATING SULFIDE MINERALS OF NICKEL BY FROTH FLOTATION, THE IMPROVEMENT WHICH COMPRISES CONTACTING A SULFIDE NICKEL OR IN THE FORM OF A PULP WITH A FLOTATION COLLECTOR COMPRISING A COMPOUND CORRESPONDING TO THE FORMULA
 2. The process of claim 1 wherein X is O.
 3. The process of claim 1 in which R is H or a linear or branched alkyl group of one to six carbons.
 4. The process of claim 3 in which R is methyl, ethyl, propyl or isopropyl.
 5. The process of claim 1 in which R1 is -CH2-CH2-, -CH(CH3)-CH2-, -CH2- CH(CH3)- or -CH2-CH2-CH2-.
 6. The process of claim 1 in which R2 is an alkyl or alkenyl group of three to six carbons.
 7. The process of claim 1 in which R is H, methyl, ethyl, propyl or isopropyl, R1 is -CH2-CH2-, -CH(CH3)-CH2-, -CH2-CH(CH3)- or -CH2-CH2-CH2-and R2 is an alkyl or alkenyl group of three to six carbons.
 8. The process of claim 7 in which R is methyl, ethyl, propyl or isopropyl.
 9. The process of claim 7 in which R is H, R1 is -CH2-CH2-, R2 is isopropyl and X is O.
 10. The process of claim 7 in which R is ethyl, R1 is -CH2-CH2-, R2 is isopropyl and X is O. 